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JAKE TAPPER, CNN HOST: Welcome back to THE LEAD. I'm Jake Tapper. We're going to keep an eye on the tornado activity happening right now in Oklahoma, but for now we'll turn to some other national news. It happened, again, a suspicious letter mailed to President Barack Obama, but intercepted at a screening facility before it got to the White House.

A law enforcement source says the letter appears to be similar to two others mailed to New York City Mayor Michael Bloomberg and the group "Mayors Against Illegal Guns," which Bloomberg founded and he co- chairs. Initial testing on those two letters not the one to Obama came back positive for ricin, which has become the deadly poison dujour for mail attackers.

A source tells CNN that this was written in both of those two letters found earlier, quote, "You will have to kill me and my family before you get my guns. Anyone who wants to come to my house will get shot in the face. The right to bear arms is my constitutional God given right and I will exercise that right until the day I die," unquote.

It is not clear what was written in the letter to President Obama. That letter has been sent to the FBI for testing so we do not know if it had ricin on it yet. A source says it was postmarked in Shreveport, Louisiana just like the ones sent to Bloomberg and his gun control group.

Remember, someone already sent a ricin-tainted letter to the president seven weeks ago. Not just to him but also Mississippi Senator Roger Wicker and also to a judge. In those earlier cases authorities first arrested the Elvis impersonator on the right of your screen, but he was later cleared and they arrested the martial arts instructor on the left of your screen who has been in jail without bail for a month. The bizarreness of that case aside, ricin is no laughing matter. It is lethal and there is no antidote.

I want to bring in Congressman Peter King, Republican from New York and member of the House Homeland Security Committee and the House Permanent Select Committee on Intelligence. Congressman King, thanks for being here. Have you heard anything about this latest letter to President Obama? Do you believe it is connected to the ones sent to Mayor Bloomberg and his group? REPRESENTATIVE PETER KING (R), NEW YORK: Well, you know, the investigation is obviously in its early stages, but the law enforcement people I've spoken to say that the letters are virtually identical. There was the two to Mayor Bloomberg, one in New York, one in D.C., and then one to President Obama. So what I'm being told now is that the letters are identical but, again, it's at an early stage. That is what I'm hearing from people in law enforcement.

TAPPER: This of course seems to be separate from the cases in April. Why do you think there has been such a sudden rash of mail attacks involving ricin? Do law enforcement sources speculate about that?

KING: Again, part of it is copy cat. It's out there and got so much attention when it happened with Senator Wicker and it's really not that difficult. I'm no expert on this but something can be done. This is really deadly. This is a different type thing than anthrax. As you said, there is no antidote for it.

Cipro is not going to help you, anything like that. So it is deadly and certainly gets an impact. The fact you're talking about it tonight and the media across the country is talking about it certainly makes an impact and if a person feels that strongly about the gun issue in their own perverse way, they may feel this is a way of sending a national signal.

TAPPER: As you say, the motive at least as stated as we take it face value and perhaps we should that, but that motive seems clear, as it was declared. Are elected officials do you think being targeted here for advocating further restrictions on firearms ownership?

KING: Well, that's what it would seem. It could also be somebody on the other side, you know, trying to make their point by, you know, blaming the people who believe in gun rights. I am on Mayor Bloomberg's side on this issue, by the way. I support the mayor and his efforts as far as gun legislation is concerned.

But yes, there are always crack pots, whackos you want to call them, extremists, zealots, on all sides of these issues using the extreme side of the issue so it could well be someone who is a fanatical gun rights supporter.

But again, my experience is that fanaticism is across the board, on the right and the left and something we should not encourage in any way. People in public life have an obligation to keep that in mind when they make statements or make speeches realizing that there are people out there who can overly respond to what we say.

TAPPER: Congressman Peter King, thank you as always for coming in and talking to us.

KING: Jake, let me just say all of us, our thoughts and prayers are with the people in Oklahoma. They have gone through hell and it's just terrible.

TAPPER: All right, thank you so much. Appreciate it. I'm going to make a safe assumption that among your copies of "Vogue" and "Sports Illustrated" at home you do not have the latest issue of "Inspire" magazine that's an English language propaganda tool put out by al Qaeda in the Arabian Peninsula.

They are the ones who wrote, quote, "Make a bomb in the kitchen of your mom," directions for a pressure cooker bomb that were strikingly similar to the ones allegedly used by the Tsarnaev brothers for the Boston marathon attacks.

CNN has now obtained the latest issue of "Inspire" magazine, which is celebrating the Boston marathon attack and praising the Tsarnaev brothers calling them "brothers" and, quote, "Yesterday it was Baghdad. Today it is Boston. The question of who and why should be kept aside. You should be asking where is next," unquote, a chilling comment.

Joining me now is Paul Cruickshank, a contributor and research fellow for the Center on Law and Security at the New York University School of Law. They are putting the Boston marathon terrorist attacks front and center. What message do you see that they are sending here?

PAUL CRUICKSHANK, CNN CONTRIBUTOR: They're trying to capitalize on this to inspire more attacks and saying we inspire this. Our magazine inspired this. These two brothers downloaded bomb making instructions from our magazine and then carried out this attack. They can show our followers in the west what they can be capable of, these types of lone wolf attacks. They are trying to inspire more of this kind of terrorism.

TAPPER: They also talk about in this magazine the machete attack in the U.K. That is a pretty quick turn-around to put out, put that out. Explain that. Why that propaganda value is so important to talk about all of these different events and current events.

CRUICKSHANK: Well, that is a very quick turnaround. It was just about a week ago. So they put it out very quickly. They feel this is another victory for them. This is going to inspire more of these sorts of attacks. They also refer to an attack against the French soldier in Paris on Saturday so very recent events are mentioned in this "Inspire" magazine.

This is propaganda to encourage more lone wolf style terrorism in the west. They recognize this is very hard to protect against. You've got just two or three people watching these attacks and they don't have connections to overseas terrorist groups. They are saying don't come and join us or train with us. Stay home and we'll give you the instructions you need to carry out these attacks.

TAPPER: Chilling. Thank you so much, Paul Cruickshank. Appreciate it.

The man President Obama is likely to nominate as the new director of the FBI may be a Republican, but that doesn't mean he isn't the darling of a lot of the civil libertarians in Washington. That's coming up in our "Politics Lead." Stay with us. (COMMERCIAL BREAK)

TAPPER: Welcome back to THE LEAD. I'm Jake Tapper. We are keeping an eye on the new tornado threat happening right now in Oklahoma. But first, we're going to come to the "Politics Lead." President Obama has reportedly picked a head of the FBI surprisingly a Republican. But to hear some tell it James Comey has had a career that at times reads like the exploits of a civil liberties super hero.

James Comey was a high ranking Justice Department official during the George W. Bush administration and regardless of your politics or your perspective you've got to admit he's got spine. Comey famously stood up to White House Counsel Alberto Gonzalez and to President George W. Bush's Chief of Staff Andrew Card back in 2004.

When they were reportedly trying to convince Attorney General John Ashcroft who was lying very sick in a hospital bed, they wanted Ashcroft to sign an extension on a controversial warrantless domestic eavesdropping program. Comey told the story in a Senate Judiciary hearing back in 2007.

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JAMES COMEY, FORMER DEPUTY ATTORNEY GENERAL: I raced to the hospital room that Mr. Ashcroft was lying down in the bed. The room was darkened. It was only a matter of minutes that the door opened and in walked Mr. Gonzalez carrying an envelope and Mr. Card. They came over and stood by the bed and Mr. Gonzalez started to discuss why they were there to seek his approval.

Attorney Ashcroft then stunned me. He lifted his head off the pillow and in very strong terms expressed his view of the matter and as he laid back down he said, but that doesn't matter because I'm not the attorney general. There is the attorney general and he pointed to me.

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TAPPER: Now, of course, Comey's record civil libertarians point out is much more mixed than that one cinematic anecdote might suggest. He has prosecuted everybody from the New York mob boss John Gambino to Martha Stewart so it is an interesting choice, but can he get the nod from the Senate?

Here to talk about it, Mike Allen, the chief White House correspondent for "Politico" and Susan Page, the Washington Bureau chief of "USA Today." Now Susan, progressives have had problems with Comey in the past for other issues, a murky role in authorizing the waterboarding. How do you think the nomination process is going to go?

SUSAN PAGE, WASHINGTON BUREAU CHIEF, "USA TODAY": I think it's going to go barring disclosures we don't know yet. I think it's going to go smoothly for Republicans, served in a Republican administration, contributed to John McCain and Mitt Romney's presidential campaigns so good for Republicans. But for Democrats here is a political figure to head the FBI who should have an easy confirmation process at the time. The White House would like to get immigration through the Congress. TAPPER: Mike, where do you see opposition coming from or at least tough questions? Do you think it's more liberals who are going to have tough questions for him in the Senate?

MIKE ALLEN, CHIEF WHITE HOUSE CORRESPONDENT, "POLITICO": Any tough questions, Jake, are going to be grandstanding. We just saw the best audition tape ever and you'll see why the president doesn't get a bipartisan halo. This is someone who is nonpartisan. We're told specifically Senator Chuck Schumer who might be inclined to ask tough questions really likes Comey and has a good relationship with him.

This is also a very personal pick for the president. As you know most people the president nominates he never sees again, probably doesn't think about again. The FBI director every Tuesday afternoon in the situation room, the other situation room, the president meets with his Homeland Security Council and the FBI director is there. He is going to spend the next three years with him.

TAPPER: It's an interesting pick because it's a Republican. Susan, do you think the president did that on purpose because of how ugly things are in Washington right now?

PAGE: I think it is probably helpful for the president to have a Republican in such an important job and it is a job that is important for Americans for FBI directors served for 10 years. So they should transcend some kind of politics of the moment.

TAPPER: Is this a statement that the White House is making, Mike, do you think, because of all the scandals that they're dealing with or controversies, whatever you want to call them, the IRS, etcetera? Do you think that this pick comes with those controversies, scandals in mind? Is that part of it?

ALLEN: This was going on the track long before that. It certainly has the effect of helping the president. The fact that we're talking about that rather than the IRS, all these little mini things that the White House is doing every single day to try to turn the topic as we've just seen on your air today, events can change things in a hurry.

PAGE: He did work for a big hedge fund and Chuck Grassley, the senator from Iowa indicated this afternoon he has questions about the prosecution of Wall Street figures pending so that could be a subject.

ALLEN: We agree that is going to be -- just as we do, when we sort of know where things are headed the senators ask a question in a different way and draw blood less.

Coming up, the story of the mayor who allegedly smoked crack, not the one from this town but a different town, it gets even weirder. Toronto Mayor Rob Ford has repeatedly said video of him smoking crack does not exist, but now one report says he told members of his staff that he knows where that video is. He just spoke to reporters again. We'll tell you what he said.

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TAPPER: Welcome back to THE LEAD. It's time for the "World Lead." His staff is leaving him in droves, but the besieged Toronto mayor is sticking with his story that he does not smoke crack and he is ignoring reporters' incessant questions about it. Here he is just minutes ago saying farewell to two staffers who left today.

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MAYOR ROB FORD, TORONTO: I've been interviewing candidates all week and look forward to hiring new staff as soon as possible. Thank you very much.

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TAPPER: It went on like that. Have you done this, anything else? Have you done that, anything else? More than 8,000 inquiring minds have pitched in more than $200,000 to the crowd funding web site Indy Go-Go to buy a video for gawker.com that supposedly shows the mayor smoking crack.

The only problem is Gawker and "The Toronto Star" newspaper who first launched the story into the media stratosphere still cannot seem to find the people who told them they have the evidence. Mayor Ford told the press last week that the video does not exist.

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FORD: I do not use crack cocaine nor am I an addict of crack cocaine. As for a video I cannot comment on a video that I have never seen or does not exist.

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TAPPER: But today the story is taking an even weirder turn. Kevin Donovan from the "Toronto Star" joins me now. Kevin, welcome. You say you've seen this cell phone video with your own eyes and in addition to that you have reported that according to your sources the mayor told his staff two weeks ago that he knows where this video is. That's at odds with his public statements. What is going on here?

KEVIN DONOVAN, "TORONTO STAR": Well, this mayor, both when he was counselor and now mayor for a couple years, is no stranger to issuing denials and dismissing things that the media have reported. This is just another one. What we've reported today is that he definitely made a comment, giving an apartment unit and a floor and actual municipal address where this video could be found happens to be an area where we met this -- the person who showed us the video. Yes, I did see it with my own eyes along with my colleague Robin Doolittle and the thing is real.

TAPPER: You're not the first person to say they've seen this cell phone video. John Cook from Gawker here in the U.S. has also said he's seen it. Why hasn't it been passed around already do you think? Wouldn't someone have shared it by now? Wouldn't it have leaked by now if it exists?

DONOVAN: In the wired world it certainly is amazing this hasn't gotten out. When we saw it, it was on an iPhone and my understanding for what John from Gawker has written that he saw it also on an iPhone. We have not heard that there are specific other copies out there. We do know that other people have seen this video and I'm confident that it is going to see the light of day, but it seems to be in hiding for the foreseeable future.

TAPPER: Kevin, the -- there are new resignations today. Tell us about that.

DONOVAN: Yes, this afternoon there were two resignations -- a policy adviser, Brian Johnson, who is a policy adviser to Mayor Ford and also a junior executive assistant to the mayor who also as quit. My understanding is that they quit on principle. They just couldn't stand it there any longer.

TAPPER: How many people totally -- how many people in total have resigned and does this suggest that his goose is cooked that this is going to be the end of the mayor?

DONOVAN: Well, this mayor has incredible staying power. It is quite possible that he will just, you know, run the table and hope that he can be re-elected in 18 months. There is no mechanism as I understand it to remove him. There have been five so far including his chief of staff.

Many of the new people who have come in who are still there are former football players or people involved in his football program. He's got his old high school coach, Dave Price, who figures in this video story as somebody who was talking about going and getting the video. He is there. So there are certainly people staffing the office. They don't have any experience in helping to run Canada's largest city.

TAPPER: All right, Kevin Donovan, thank you so much.

Major storms are pummelling parts of Oklahoma with some areas still under a tornado warning. We'll have the latest on their track, next.

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TAPPER: Welcome back. We're keeping a close eye on the severe weather in the plains right now. There are reports of three still unconfirmed reports, tornadoes south of Stillwater, Oklahoma. That's about an hour north of Oklahoma City. The state of Oklahoma is, of course, still reeling from an EF-5 tornado that laid waste to the town of Moore last week killing 24 people. At the moment we have not heard reports of injuries or damage from today's outbreak.

That's it for me. I'm Jake Tapper. I leave you in the hands of Wolf Blitzer who will have much more on the Oklahoma storm.